1. Field of the Invention
This is a further development in the field of liquid chromatography, and relates particularly to means for injecting a sample fluid into a high-pressure stream of carrier fluid.
2. Description of the Prior Art
In liquid chromatography, the sample fluid to be analyzed is often mixed with a carrier fluid of known composition for transport through a chromatographic column. In terms of minimizing the time required for analyzing a succession of samples, it is advantageous for the carrier fluid to flow at uninterruptedly high pressure into the chromatographic column. However, unless each quantity of sample fluid to be analyzed is introduced into the high-pressure carrier stream at a comparable high pressure, special sealing techniques must be devised to accommodate the pressure differential between the sample fluid and the stream of carrier fluid. Such special sealing techniques as have been developed to date are not completely reliable and frequently leak, thereby causing inaccuracy in the analysis. The alternative of providing for interruption of the high-pressure flow of the carrier fluid so as to permit introduction of a quantity of sample fluid at low pressure into the carrier stream is disadvantageous in terms of wear and tear on pump components and control elements. The preferable approach is to introduce the sample fluid into the high-pressure carrier stream at a comparable high pressure. An apparatus and method for accomplishing same is disclosed on copending patent application Ser. No. 493,593, filed Aug. 1, 1974, by Richard E. Klee and Joseph A. Varozza and assigned to Varian Associates.